FARS (FARSITE)

FARSITE is a two--dimensional fire spread model that maps predicted fire progression and fire behavior under a variable fire environment.

To run the FARSITE model in the FMSF, there are three required and one optional input:

  • A fuelscape GeoTIFF

  • An input file

  • An ignition shapefile

  • A barrier shapefile (optional)

 

GeoTIFF

The FARSITE model requires a GeoTIFF landscape/fuelscape.  The GeoTIFF is uploaded to the FMSF, prior to making a run request (see Upload a GeoTIFF), and the ID is used when making the model run request (see Run a Model).

The following bands must be present in the GeoTIFF in this order (additional bands may exist starting with #9):

Band #

Band Name

Units

1

Elevation (DEM)

meters

2

Slope

degrees

3

Aspect

degrees

4

Fuel Model

categorical

5

Canopy Cover

percent

6

Canopy Height

meters * 10

7

Canopy Base Height

meters * 10

8

Canopy Bulk Density

kg/m3 * 100

 

Current cell limits for FARSITE within the FMSF is 54,804,196. If you are unsure how many cells comprise the GeoTIFF you are using to run the model, Retrieve Minimum Model Run Resolution for a GeoTIFF can be used to determine both the cell counts and the minimum resolution the model may be run.

 

Ignition & Barrier Shapefiles

FARSITE also uses two spatial inputs: ignition shapefile (required) and barrier shapefile (optional).

To use a shapefile, it must be uploaded to the system prior to attempting to run the model as the assigned ID is used to specify which file to use. For details on shapefile functionality in the FMSF see the Shapefile Functionality section.

The geometry type of an ignition shapefile can be point, polygon, polyline, or multipoint.

The geometry of a barrier shapefile can be polygon or polyline.

 

Input file

The various input and output switches included in the input file (*.txt or *.input) passed to the FMSF are documented in the following sections with the valid ranges for each switch.

Example FARSITE input file including all the input and output switches.

 

Model Setting Switches

FARSITE_TIMESTEP: 60 

FARSITE_DISTANCE_RES: 30 

FARSITE_PERIMETER_RES: 30 

FARSITE_MIN_IGNITION_VERTEX_DISTANCE: 20.00 

FARSITE_ACCELERATION_ON: 1

 

FARSITE_TIMESTEP: X where X is the time in minutes for maximum amount of time that the conditions at a given point are assumed constant so that the position of the fire front can be projected. The positions of all fires will be projected over this time step so that possible mergers can be computed.

  • Valid range: 30-60 

FARSITE_DISTANCE_RES: X where X is the distance in meters. The FARSITE model will check for new fire characteristics when this distance has been covered within a time step.

  • NOTE: The value must be a multiple of the GeoTIFF resolution.

  • Valid range: 30-10000 (or the landscape resolution if it is greater than 300)

FARSITE_PERIMETER_RES: X where X is the distance, in meters, between the ignitions placed along the fire perimeter at each time step

  • NOTE: The FARSITE_PERIMETER_RES must be greater than or equal to the FARSITE_DISTANCE_RES.

  • NOTE: The value must be a multiple of the GeoTIFF landscape resolution.

  • Valid range: 30-10000 (or the landscape resolution if it is greater than 300)

FARSITE_MIN_IGNITION_VERTEX_DISTANCE: X where X is the minimum distance, in meters, between fire ignition vertices placed along the given ignition shapefile.

  • Valid range: 7-10000

FARSITE_ACCELERATION_ON: X where X is either 0 for no acceleration or 1 to use acceleration.

  • Valid range: 0, 1

 

Initial Fuel Moisture Switches

FUEL_MOISTURES_DATA: 3 

0 3 5 7 57 85 

121 4 6 8 62 88 

163 2 5 7 65 95 

 

FUEL_MOISTURES_DATA: X where X is the number of initial fuel moisture data entries. Immediately following this line should be X lines of initial fuel moisture inputs.

  • Valid range: 1-59

Initial fuel moisture entries must include the following six integers in order per line, space, or tab delimited:

  • Fuel model number

    • 0 is required, this is the default moistures to use when a fuel model is encountered that does not have an entry in the input file

    • Valid range: 0, 1-13, 101-109, 121-124, 141-149, 161-165, 181-189, 201-204

  • 1-hr dead fuel moisture content percent

    • Valid range: 2-300

  • 10-hr dead fuel moisture content percent

    • Valid range: 2-300

  • 100-hr dead fuel moisture content percent

    • Valid range: 2-300

  • Live herbaceous fuel moisture content percent

    • Valid range: 2-300

  • Live woody fuel moisture content percent

    • Valid range: 2-300

 

Wind Switches

GRIDDED_WINDS_GENERATE: Yes

GRIDDED_WINDS_RESOLUTION: 180

 

GRIDDED_WINDS_GENERATE: val where val is ‘Yes’ for generate gridded winds or ‘No’ for do not generate.

  • NOTE: Gridded winds are calculated using the WindNinja model embedded within FARS.

  • NOTE: This switch will be ignored if the GRIDDED_WINDS_RESOLUTION is not present.

  • Valid range: Yes, No

GRIDDED_WINDS_RESOLUTION: X where X is the desired resolution for the gridded winds in meters.

  • NOTE: WindNinja requires a large amount of memory to run. To ensure runs are completed in a reasonable timeframe, the FMSF will adjust the GRIDDED_WINDS_RESOLUTION as needed. Initially, this adjustment will be 2 times the GeoTIFF landscape/fuelscape resolution. Subsequent FMSF adjustments to GRIDDED_WINDS_RESOLUTION may be required to keep the WindNinja grid below 1 million pixels. The GRIDDED_WINDS_RESOLUTION used to run the model can be found in the run metadata and in the input file returned when downloading the model outputs.

  • Valid range: 30-10000

 

Weather Stream Switches

RAWS_ELEVATION: 6119

RAWS: 384

2012 6 4 0000 71 19 0.00 0 0 0

2012 6 4 0100 68 20 0.00 0 0 0

2012 6 4 0200 66 21 0.00 0 0 0

2012 6 4 0300 64 22 0.00 0 0 0

2012 6 4 0400 62 23 0.00 0 0 0

2012 6 4 0500 61 23 0.00 0 0 0

. . .

2012 6 19 2300 69 19 0.00 0 0 0

 

RAWS_ELEVATION: X where X is the elevation in feet of the RAWS (Remote Access Weather Station). 

  • Valid range: -1000-20000

RAWS: X where X is the number of sequential hourly weather data entries, followed by X number of hourly weather data records, 1 per line.

Weather data entries must include the following values in order per line, space, or tab delimited:

  • Year in the YYYY format.

    • Valid range: Any

  • Month in the M or MM format.

    • Valid range: 1-12

  • Day in the DD format.

    • Valid range: 1-31

  • Time of day (military) in HHMM format.

    • Valid range: 0000-2400 (valid times within that range)

  • Temperature in Fahrenheit at the time of the record.

    • Valid range: -50-150

  • Relative humidity as percent at the time of the record.

    • Valid range: 0-100

  • Hourly precipitation total for the hour ending at the time of the record in inches.

    • Valid range: 0.00-10.00

  • 20 ft wind speed in MPH at the time of the record.

    • Valid range: 0-150

  • Azimuth of the 20 ft wind at the time of the record.

    • Valid range: 0-360

  • Cloud cover as percentage at the time of the record in percent.

    • Valid range: 0-100

 

Start and End Switches

FARSITE_START_TIME: 07 23 1200 

FARSITE_END_TIME: 07 26 1959 

 

FARSITE_START_TIME: date/time where the date/time is the month, day, and military time (space delimited) of the fire start time. 

  • NOTE:  This can be overridden if burn periods (FARSITE_BURN_PERIODS) are also specified.

  • NOTE: The hourly weather stream must contain the FARSITE start time. 

  • Valid range: MM = 1-12, DD = 1-31, HHRR = 0000-2400 (valid times within that range)

 

FARSITE_END_TIME: date/time where the date/time is the month, day, and military time (space delimited) of the fire end time (end of simulation).

  • NOTE:  This can be overridden if burn periods (FARSITE_BURN_PERIODS) are also specified.

  • NOTE: The hourly weather stream must contain the FARSITE end time. 

  • Valid range: MM = 1-12, DD = 1-31, HHRR = 0000-2400 (valid times within that range)

 

Burn Period Switches

FARSITE_BURN_PERIODS: 4

08 07 1000 1800

08 08 1000 1800

08 09 1000 1800

08 10 1000 1800

 

FARSITTE_BURN_PERIODS: X where X is the number of burn period entries, immediately followed by X burn period entries on the next X lines in the inputs file.

  • NOTE: This is an optional input, if no burn periods are used the fire will burn for the entire simulation period.

  • NOTE: Burn periods must be entered in chronological order.

  • NOTE: There can be more than one burn period per day, but they must not overlap.

  • NOTE: It is not an error to have a mismatch between the FARSITE_TIMESTEP and the length of a burn period but it is recommended that they should be consistent.

  • Valid range: 0-180

 

Burn period data entries must include the following values in order per line, space, or tab delimited:

  • Month in the M or MM format.

    • Valid range: 1-12

  • Day in the DD format.

    • Valid range: 1-31

  • Burn period start time (military) in HHMM format.

    • Valid range: 0000-2400 (valid times within that range)

  • Burn period end time (military) in HHMM format.

    • Valid range: 0000-2400 (valid times within that range)

 

Canopy Characteristic Switches

FOLIAR_MOISTURE_CONTENT: 100 

CROWN_FIRE_METHOD: Finney 

 

FOLIAR_MOISTURE_CONTENT: X where X is the fuel moisture content in percent. 

  • Valid range: 2-200

CROWN_FIRE_METHOD: cfmethod where cfmethod is either ‘ScottReinhardt’ or ‘Finney’. 

  • Valid range: ScottReinhardt, Finney

Spotting Switches

FARSITE_SPOT_GRID_RESOLUTION: 15.00 

FARSITE_SPOT_PROBABILITY: 0.05 

FARSITE_SPOT_IGNITION_DELAY: 0 

FARSITE_MINIMUM_SPOT_DISTANCE: 30 

SPOTTING_SEED: 215217 

 

FARSITE_SPOT_GRID_RESOLUTION: X where X is the resolution of the background spotting grid.

  • NOTE the resolution should typically be a divisor of the GeoTIFF landscape resolution. Thus, if the landscape resolution is 30 meters, the spot grid resolution could be 30, 15, 10, 7.5, 6, 5, 4, 3, 2, or 1.

  • Valid range: 1-10000

FARSITE_SPOT_PROBABILITY: X where X is the probability that a spot causes an ignition.

  • Valid range: 0-1

FARSITE_SPOT_IGNITION_DELAY: X where X is the number of minutes to delay an ignition caused by spotting.

  • NOTE if FARSITE_SPOT_PROBABILITY is 0, this switch is not needed and will be ignored.

  • NOTE this value should typically be set to 0 as the FARSITE model already incorporates travel time for each ember.

  • Valid range: 0-60

FARSITE_MINIMUM_SPOT_DISTANCE: X where X the minimum distance in meters a spot must travel for it to start a new fire.

  • Valid range: 0-10000

SPOTTING_SEED: X where X is typically a randomly generated value; however, it can be specified in the input file.

  • NOTE if MTT_SPOT_PROBABILITY is 0, this switch is not needed and will be ignored.

  • NOTE if MTT_SPOT_PROBABILITY is >0, this switch is an optional input.

  • Valid range: 0-999999

 

Barrier Fill Switch

FARSITE_FILL_BARRIERS: 1 

 

FARSITE_FILL_BARRIERS: X where X is either 0 for false (no barrier fill) or 1 for true (fill the barriers).

  • Valid rage: 0, 1

 

Output Switches

ARRIVALTIME:

FLAMELENGTH:

SPREADRATE:

SPREADDIR:

CROWNSTATE:

 

The FARSITE fire behavior model will produce up to nine gridded output layers as well as three miscellaneous output types. 

Outputs are requested by using the appropriate switch(s) in the input file (see the table for details). The order the switch(s) are listed in the input file correlate to the band order in the output GeoTIFF.

Grid outputs (part of the multi-band GeoTIFF)

Switch

Output Layer 

Units 

ARRIVALTIME:

FARSITE Arrival Time 

minutes 

FLAMELENGTH:

FARSITE Flame Length 

meters 

SPREADRATE:

FARSITE Rate of Spread 

m/min 

INTENSITY:

FARSITE Fireline Intensity 

kW/m 

HEATAREA:

FARSITE Heat per Unit Area 

kJ/m2 

SPREADDIR:

FARSITE Spread Direction 

degrees 

CROWNSTATE:

FARSITE Crown Fire Activity 

class 

RXINTENSITY:

FARSITE Reaction Intensity 

kJ/m2-min 

IGNITION:

FARSITE Ignition 

class 

 

Non-grid outputs

Switch

Description 

FARSITEPERIMETERS:

Shapefile with perimeter for each time step

FARSITESPOTFIRES:

Shapefile with the locations where spot fires occurred

FARSITETIMINGS:

Text file containing the input information for the model run, information regarding the system on which the model was run, the number of vertices (not cells) on the edge of the landscape that burned, as well as the amount of time that it took the FARSITE model to complete.

 

Switches Not Currently Supported by the FMSF

The FMSF does not currently support all switches available within the FARSITE model. Those not supported are listed below.

CUSTOM_FUELS_FILE: Filename where filename is the name of the desired custom fuels file to use.

  • The FMSF does not support custom fuel models currently. 

RAWS_UNITS: X where X is either the string English or Metric indicating the units for the weather data in the RAWS section as well as the RAWS_ELEVATION.

  • The FMSF only accepts English

ROS_ADJUST_FILE: Filename where file name is the name of the rate of spread adjustment file to use.

GRIDDED_WINDS_DIRECTION_BIN: X where X is the size in degrees to use for gridded winds direction tolerance.

GRIDDED_WINDS_SPEED_BIN: X where X is the size in MPH to use for gridded winds speed tolerance.